Ap III midterm The Cardiovascular System The Heart

Anatomyof the Heart Location of the heart o Rests on the diaphragm near midline of thoracic cavity o Lies in the mediastinum (anatomical region that extends from the sternum to the vertebral column, from the 1st rib to the diaphragm & in between the lungs) o About 2/3 of the mass of the heart lies to the left of the body’s midline o Apex: formed by the tip of the left ventricle & rests on diaphragm— directed anteriorly, inferiorly and to the left o Base: opposite of apex & is its posterior aspect—formed by the atria (upper chambers) and mostly the left atrium o Anterior surface: deep to sternum and ribs o Inferior surface: part of heart between apex and right surface & rests on diaphragm o Right surface: faces right lung & extends from the inferior surface to the base o Left surface: faces left lung and extends from base to apex Pericardium o Membrane that surrounds and protects the heart o Confines heart to its position in the mediastinum, while allowing sufficient freedom of movement for vigorous and rapid contraction o Consists of 2 main parts:  Fibrous pericardium: superficial- composed of tough, inelastic, dense irregular connective tissue  Resembles a bag that rests on and attaches to diaphragm  Open end is fused to connective tissues of blood vessels entering and leaving the heart  Prevents overstretching  Provides protection  Layersoof the3 layers  Anchors heart in mediastinum  Near the apex of the heart, it is partially fused to the central tendon of the diaphragm, so movement of the diaphragm facilitates movement of blood by the heart Serous pericardium: deep- thinner, more delicate membrane that forms a double layer around the heart  Parietal layer of serous pericardium: outer layer- fused to the fibrous pericardium  Visceral layer of serous pericardium: also called the epicardium; adheres tightly to the surface of the heart  b/w the parietal and visceral layers of the serous pericardium is a thin film of lubricating serous fluid known as pericardial fluid, that reduces friction b/w layers of serous pericardium as the heart moves  space that contains the few milliliters of pericardial fluid is the pericardial cavity